Due to rising rates of mobile device usage, ultra-dense networks (UDN) are being increasingly used to augment the capacity of wireless communication systems. In an ultra-dense network it is important to ensure that the data flowing to and from an active user node is not subjected to significant changes in the channel conditions, such as a sudden significant decrease in the signal to interference plus noise ratio (SINR) of the signal. Since ultra-dense networks operate mainly in LoS conditions, a large vehicle or other physical disturbance passing between the user node and the remote radio unit to which it is connected can cause the radio link to be lost or severely degraded. These unexpected changes in channel conditions may lead to a significant decrease in throughput, increased latency, and an overall poor end-user performance or experienced quality of service (QoS).
Conventional wireless communication systems typically adjust connectivity of a moving user node using handoff or handover techniques, where a user node is moved from one serving access node to another. Conventional systems also detect “blank spots” or areas where there is poor radio coverage and adjust connectivity of user nodes in those areas to improve overall channel quality. However, conventional systems mechanically reposition an antenna in a reactive fashion after degradation of the signal has been detected, and the amount of time taken to physically move an antenna can be quite large resulting in less than optimal system performance. Conventional wireless systems also base detection of disturbances or blank spots on measurements made only by the user nodes so detection is based only on down link measurements. Compensation for disturbances is also typically carried out through adjustments in the user node, thus increasing the power consumption of the user node.
Conventional or state-of-the are solutions operate on a “cell-scale” considering the cell as a whole and are not able to effectively compensate for disruptions of an individual radio link or an individual user node caused by moving physical disturbances. However, ultra-dense network disruptions of individual radio links caused by moving physical disturbances typically have a significant negative impact on user node connectivity. This is because the connection between user nodes and the ultra-dense network is primarily based on low-power and/or high frequency radio-links which operate most effectively in LoS conditions.
Target tracking algorithms based on widely separated antennas are useful in detecting and tracking moving physical disturbances present in many ultra-dense networks. However, conventional target tracking methods are limited to tracking the current location of objects and do not offer solutions for predicting future disruptions of the radio links between user nodes and the ultra-dense network. Detection of degradations in channel quality of the radio links has typically been done using measurements from the user node alone and is thus unable to detect or predict radio link degradations that will be caused by the moving physical disturbances.
Thus there is a need for improved methods and apparatus for detecting, tracking, and compensating for disturbances of radio link quality in ultra-dense network caused by physical disturbances. There is also a need for improved methods and apparatus that can track physical disturbances and proactively adjust the connectivity of user nodes to avoid loss of connectivity or significant degradation of the QoS provided to the user nodes.